Lighting control systems comprising switches and dimmers have become increasingly popular, especially for applications where it is desired to Precisely control the level of light intensity in a particular room. In the simplest type of dimmer controlled lighting systems, a dimmer switch actuator is manipulated by hand, to control the setting of a variable resistor which in turn controls the switching of a solid state power control device such as a triac. The switching of the solid state power control device, in turn, varies the voltage input to the lamp to be dimmed. This type of system, incorporating a dimmer switch,
Other lighting control systems comprise touch actuator operated lighting controls which address some of the limitations associated with the manually-operated variable resistor controlled dimmer switch previously described. In one example of a touch actuator operated control system, the lamp is cycled repetitively through a range of intensities, from dim to bright, in response to extended touch inputs. When the desired intensity is reached, the touch input is removed, the cycle will stop, and the level of light intensity is set (preselected) and stored in a memory function that is typically provided by such systems. Typically, a subsequent short touch input will turn the lamp off, and a further short touch input will turn the lamp on at the set intensity level stored in the memory. While this type of device is an improvement over manually-operated dimmer switches, it requires the user to go through the cycle of intensity levels in order to arrive at a different intensity level. In addition, this type of device lacks the ability to return to a set or preset intensity level when the level is changed. A user must go through the cycle again until he or she finds the light intensity level desired. Moreover, this type of device has no ability to perform certain aesthetic effects such as a gradual fade from one light intensity level to another.
U.S. Pat. No. 4,649,323 discloses a microcomputer-controlled light control which provides a fade function. The control disclosed in that patent is operated by a pair of non-latching switches which provide inputs to a microcomputer. The microcomputer is programmed to determine whether the switches are tapped or held (i.e., whether they are touched for a transitory duration or for a longer period of time). When a switch is held, the light intensity is either decreased or increased, and release of the switch causes the intensity setting to be entered into a memory. If the control is operating at a static light intensity level, a tap of a switch will cause the light intensity level to fade to a preset level, either off, full on, or an intermediate level. A tap while the light intensity level is fading will cause the fade to be terminated and cause the light intensity level to shift immediately and abruptly to either full on or full off, depending on which switch is tapped. This type of control, however, is not without drawbacks of its own. For example, a single tap by a user is interpreted in either of two very different ways (initiate fade or terminate fade), depending on the state of the control at the time the user applies the tap to a switch. This can be confusing to a user, who may erroneously terminate a fade when it is desired to initiate a fade, and vice versa. In addition, it is not possible to reverse a fade by a subsequent tap of the same switch while a fade is in progress. Instead, a tap while the control is fading in one direction will not reverse the direction of the fade but will cause the control to "jump" to either full on or full off. An abrupt shift from a low intensity level to full on, or from a high intensity to no light at all (full off), can be quite startling to the user and others in the area (and even dangerous, if the user and others are suddenly plunged into darkness).
The control disclosed in U.S Pat. No. 4,649,323 also lacks a long-duration fade to off, as do the other prior control designs. In many cases, it is desirable for a user to be able to have the lights fade out gradually. For example, a user may wish to turn out bedroom lights before retiring, but still have sufficient light to safely make his or her way from the control location to the bed before the lights are completely extinguished. There may also be situations where the night staff of a large building may need to extinguish ambient lights from a central location which is located some distance away from an exit, and may need a level of illumination in order to walk safely to the exit. These features would not be possible with the prior control, which would offer the user either almost immediate darkness or a constant level of intensity throughout the night, neither of which would be acceptable.
Commonly assigned U.S. Pat. Nos. 4,575,660, 4,924,151, 5,191,265, 5,248,919, 5,430,356, and 5,463,286, disclose various lighting control systems in which lamps or groups of lamps, in one or more zones, are varied in brightness to produce several different scenes of illumination. The level of brightness of the lamps constituting each lighting group is displayed to the user by either the number of light emitting diodes, LED's illuminated in a linear array of the LED's, or the position of a potentiometer slider in a linear track.
U.S. Pat. Nos. 5,191,265, and 5,463,286 disclose wall mounted programmable modular control systems for controlling groups of lights in one or more zones. In these systems, the lights are controlled by a master control wall module, a remote wall unit, and by a remote hand held control unit. The hand held unit communicates to the master control module by conventional infrared (IR) transmission techniques.
The lighting control device in U.S. Pat. No. 5,248,919 has all of the light control features needed to effectively and safely control the state and intensity level of one or more lights. However, this device lacks many desirable features such as wireless remote controllability, programmability, the ability to lock and unlock a preset function and a delayed off. In many cases, it is desirable for a user to be able to have one or more lamps fade to a pre-selected intensity level or state, or to fade to off after a variable delay time. It would be even more useful and desirable to be able to remotely control and program the preset light intensities of one or more lamps associated with one or more lighting scenes.
Another lighting device known in the art as "Onset Dimmer OS600" is manufactured by Lightolier Controls, Inc. Unlike the present invention, which allows a user to selectively lock and unlock a stored preset light intensity level with an actuator, which also performs other functions, the prior art Lightolier device cannot unlock the preset light intensity when stored. In other words, the Lightolier device can only lock a different preset light intensity into its memory. Further, unlike the present invention, the Lightolier device uses a separate dedicated switch with a separate dedicated actuator in order to lock in a preset light intensity level.
There is thus a need for an improved lighting control system which offers advantages not possible with prior controls while avoiding the drawbacks of the prior controls. The present invention fills that need.